Predictive value of the first-trimester β-hCG/PAPP-A ratio for gestational diabetes mellitus: a retrospective cohort study

Aims: To evaluate the predictive value of the first-trimester β-hCG/PAPP-A ratio for subsequent gestational diabetes mellitus (GDM) in pregnant women undergoing routine antenatal care. Methods: This retrospective cohort study was conducted in the Perinatology Department of Şanlıurfa Training and Research Hospital and included singleton pregnancies followed between January 2024 and January 2026. Maternal demographic characteristics, obstetric history, first-trimester free beta-human chorionic gonadotropin (β-hCG) and pregnancy-associated plasma protein-A (PAPP-A) values, calculated β-hCG/PAPP-A ratio, and GDM status were retrieved from electronic medical records. Women with pregestational diabetes or incomplete data were excluded. Biochemical markers were compared between women with and without GDM. Correlation analysis, logistic regression, and receiver operating characteristic (ROC) analysis were performed. Results: A total of 240 pregnant women were included, of whom 42 (17.5%) developed GDM. Women who developed GDM were older and had higher gravida and parity values. First-trimester PAPP-A levels were significantly lower, whereas the β-hCG/PAPP-A ratio was significantly higher in the GDM group. In multivariate logistic regression analysis, maternal age, lower PAPP-A, and higher β-hCG/PAPP-A ratio remained independently associated with GDM. In ROC analysis, PAPP-A showed the best discriminative performance, while the β-hCG/PAPP-A ratio demonstrated moderate predictive ability. Conclusion: Lower first-trimester PAPP-A levels and a higher β-hCG/PAPP-A ratio were associated with subsequent GDM. Although these markers are insufficient for stand-alone screening, they may contribute to early risk stratification when interpreted within a broader clinical framework.